Methods and systems for utilizing a micro-channel heat-exchanger device in a refrigeration circuit

ABSTRACT

A mini-channel heat-exchanger for a refrigeration circuit having an inlet manifold; a first return manifold; a first heat exchange pass in fluid communication between the inlet manifold and the first return manifold, the first heat exchange pass including a plurality of mini-channels; and a system charge tank in direct fluid communication with the first return manifold.

BACKGROUND OF THE INVENTION

The present disclosure is related to a refrigeration circuit. Moreparticularly, the present disclosure is related to a refrigerationcircuit having a mini-channel heat-exchanger and a system charge tank.

DESCRIPTION OF RELATED ART

Refrigeration circuits are typically used in a number of devices inorder to condition (e.g., cool, dehumidify, etc) ambient air within apredefined space such as, but not limited to, a house, a building, acar, a refrigerator, a freezer, and other conditioned spaces. A typicalrefrigeration circuit contains at least a compressor, a condenser, areceiver, a series of valves, at least one evaporator, and a systemcharge of refrigerant, which circulates throughout the circuit.

Periodically, various components of the circuit need to be serviced,repaired, and/or replaced. In order to do so, the system charge must beremoved from the components that will need servicing. One method that iscurrently used to prepare the circuit for servicing is to drain all ofthe system charge from the circuit. The system charge can not be re-usedand must be disposed of. Due to various environmental regulations, costsassociated with the proper disposal of the spent system charge can begreat. Therefore, this method may be undesirable.

A second method commonly used to prepare a circuit for servicinginvolves a “system pumpdown”. In a system pumpdown, the compressor isused to compress all of the system charge into a designated area withinthe circuit. This is advantageous in that it avoids having to remove anddispose of the system charge thereby, avoiding disposal costs and costsassociated with new system charge.

In order for a system pumpdown to be effective, the designated storagearea must have sufficient volume in which to store the compressedcharge. Problems arise, however, when modifications to the circuit aremade within the designated area, that reduce the volume available forstorage. For example, in some refrigeration circuits, the condenser isincluded in the designated storage area. Round tube and fin condenser(“RTF”) coils are frequently used in condensers. RTF coils have largeinternal volumes and provide sufficient space so that the compressedsystem charge can be stored within the storage area. However, whenmini-channel heat-exchanger (“MCHX”) coils are substituted for the RTFcoils, there is a reduction in storage volume. The heat transfercoefficient is higher for MCHX type construction than for RTF, sowhenever this type of replacement is made for coils of equal capacitythe internal volume (storage area) will be reduced. Problems will,therefore, arise during a system pumpdown as there is not sufficientspace to store the compressed system charge.

BRIEF SUMMARY OF THE INVENTION

A mini-channel heat-exchanger for a refrigeration circuit having aninlet manifold; a first return manifold; a first heat exchange pass influid communication between the inlet manifold and the first returnmanifold, the first heat exchange pass including a plurality ofmini-channels; and a system charge tank in direct fluid communicationwith the first return manifold.

A method of performing a system pumpdown in an air conditioning systemhaving a refrigeration circuit. The method includes closing a firstvalve; running a compressor until all of a system charge has beencompressed between the compressor and the first valve and liquid systemcharge fills a portion of a mini-channel heat-exchanger and a systemcharge tank, the system charge tank being fluidly connected to themini-channel heat-exchanger.

The above-described and other features and advantages of the presentinvention will be appreciated and understood by those skilled in the artfrom the following detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic representation of an exemplary embodiment of arefrigeration circuit according to the present disclosure.

FIG. 2 is a side view of a mini-channel heat-exchanger with anintegrated system charge tank in vertical orientation according to thepresent disclosure.

FIG. 3 is a top view of a first exemplary embodiment of theheat-exchanger of FIG. 2 configured for use in a vertical orientationaccording to the present disclosure.

FIG. 4 is a side view of a second exemplary embodiment of theheat-exchanger of FIG. 2 configured for use in a horizontal orientationaccording to the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and in particular to FIG. 1, an exemplaryembodiment of a refrigeration circuit according to the presentdisclosure, generally referred to by reference numeral 10, is shown.Refrigeration circuit 10 includes a system charge tank (“tank”) 12 thatcan be used to store system charge during a system pump down. In theillustrated embodiment, tank 12 is shown in use with a mini-channelheat-exchanger, which for purposes of clarity is illustrated as acondenser 14. During normal cooling using circuit 10, tank 12 is full offlowing refrigerant in a gaseous state. However, tank 12 is configuredto be filled with refrigerant in a liquid state during the system pumpdown.

Refrigeration circuit 10 includes tank 12, condenser 14, a compressor18, an evaporator 20, a first valve 22, a second valve 24, a systemcharge of refrigerant 30, and an expansion device 40. During operation,refrigeration circuit 10 operates in a known manner. Operation ofrefrigeration circuit 10 is made with reference to FIGS. 1, 2, and 3.

Compressor 18 compresses system charge 30, which flows uninterruptedfrom the compressor to condenser 14. Condensor 14 includes a pluralityof mini-channels 16 arranged in a plurality of heat-exchange passes.

Compressed system charge 30 in a gaseous state flows into condenser 14through first inlet 32 into an inlet manifold 32-1. Inlet manifold 32-1distributes the flow of charge 30 into a first pass 16-1.

Circuit 10 includes at least one condenser fan (not shown) that propelsambient outside air over condenser 14 enabling a heat-exchange betweensystem charge 30 and the ambient outside air. During the heat-exchangebetween system charge 30 and the ambient outside air, the system chargebegins to change from a gaseous state to a liquid state. After passingthrough the first pass 16, system charge 30 is collected in a firstreturn manifold 36-1.

Tank 12 is in fluid communication with first return manifold 36-1through a plurality of conduits 38-1, 38-2. In one embodiment of thepresent disclosure, plurality of conduits 38 is a set of holes so thattank 12 is integral with condenser 14. In another embodiment, pluralityof conduits 38 may be pipes so that tank 12 can be remote from condenser14.

Tank 12 has a length (L_(T)) that is substantially equal to the lengthof first return manifold 36-1 (L_(M)). In this manner, the upper conduit38-1 is positioned at or near the top of the first return manifold,while the lower conduit 38-2 is positioned at or near the bottom of thefirst return manifold. Moreover, it is preferred that a floor (F_(T)) oftank 12 is co-planar with or slightly higher than a floor (F_(M)) ofmanifold 36-1.

As seen in FIGS. 2 and 3, condenser 14 is configured for arrangement ina substantially vertical position in refrigeration circuit 10.

Return manifold 36-1 distributes the flow of charge 30 into a secondpass 16-2. After passing through the second pass 16-2, system charge 30is collected in a second return manifold 36-2, which distributes theflow of charge 30 into a third pass 16-3. After passing through thethird pass 16-3, system charge 30 is collected in a third returnmanifold 36-3, which distributes the flow of charge 30 into a fourthpass 16-4. After passing through the fourth pass 16-4, system charge 30is collected in an outlet manifold 34-1, which passes the collectedsystem charge out of condenser 14 at an outlet 34.

Accordingly, condenser 14 is illustrated by way of example as afour-pass mini-channel heat-exchanger. However, it is contemplated bythe present disclosure for condenser 14 to have as few as one pass andas many passes as desired for the proper operation of circuit 10.

Condenser 14 is fluidly connected to expansion device 40 such thatsystem charge 30 flows from the condenser uninterrupted to the expansiondevice. In some embodiments, the position of expansion device 40 can bechanged from a fully open position to a fully closed position, and anyposition therebetween. When expansion device 40 is in a fully closedposition, system charge 30, in a liquid state, will collect at theexpansion device until such time that the expansion device is opened.Expansion device 40 can be any known expansion device such as, but notlimited to, a fixed expansion device (e.g., an orifice) or acontrollable expansion device (e.g., a thermal expansion valve).

When expansion device 40 is opened, system charge 30 flows uninterruptedto first valve 22. First valve 22 can be opened or closed eithermanually or by means of electrical communication from a controller (notshown). During normal operation of refrigeration circuit 10, first valve22 is open such that system charge 30 can flow continuously toevaporator 20. As system charge 30 flows through evaporator 20, systemcharge 30 is in heat-exchange communication with a working fluid (notshown) to condition the working fluid. It is contemplated by the presentdisclosure that the working fluid can be ambient indoor air or asecondary loop fluid such as, but not limited to, chilled water orglycol.

System charge 30 then exits evaporator 20 and flows continuously tosecond valve 24. Second valve 24 can be in either an open or closedposition and its position can be changed either manually or viaelectrical communication from a controller (not shown). When secondvalve 24 is opened, system charge 30 flows uninterrupted from evaporator20 to compressor 18.

During a system pumpdown, first valve 22 is closed and compressor 18 isrun. As compressor 18 runs, compressed system charge 30 flows throughcondenser 14 wherein the system charge is changed from a gaseous toliquid state. Liquid system charge 30 will then collect at first valve22 and will then be collected in the condenser. As the level of liquidsystem charge 30 increases in condenser 14, the liquid system chargewill flow through and be collected in the condenser in a reverse orderto the normal direction of flow of the system charge. For example, theliquid system charge 30 will first be collected in outlet manifold 34-1,fourth pass 16-4, and third return manifold 36-3. The collection ofliquid system charge 30 will continue until the liquid level reaches thebottom conduit 38-2. Once the fluid level reaches the bottom conduit38-2, the liquid system charge 30 is collected in tank 12, as well as inthe remaining portions of condenser 14.

Thus, in the embodiment of FIGS. 2 and 3, tank 12 is positioned on firstreturn manifold 36-1 so that flow of system charge 30 through first andsecond conduits 38-1, 38-2 is in a horizontal direction.

Compressor 18 will continue to run until all of system charge 30 hasbeen compressed at which time second valve 24 will be closed. Uponcompletion of the pumpdown, all of compressed system charge 30 will bestored in outside portion 28 of refrigeration circuit 10 between firstand second valves 22, 24. Advantageously, outside portion 28 can bedissociated from inside portion 26 allowing for the inside portion to beserviced without replacing any of system charge 30.

Once servicing of circuit 10 is completed, outside portion 28 and insideportion 26 can be reconnected. First valve 22 and second valve 24 canthen be opened. It is contemplated that first and second valves 22, 24can be either fully opened or partially opened either manually orthrough electrical communication from a controller (not shown). As such,system charge 30 can now flow freely throughout refrigeration circuit10. Compressor 18 is turned on and system charge 30 circulatesthroughout circuit 10.

As seen in FIG. 4, an alternate exemplary embodiment of condenser 14 isshown. Here, condenser 14 is configured for arrangement in asubstantially horizontal position in refrigeration circuit 10. Moreparticularly, tank 12 is arranged with respect to a flow directionthrough mini-channels 16 so that there is an approximately ninety-degreeangle between the tank and the mini-channels.

During a system pumpdown, liquid system charge 30 collects at firstvalve 22 and will then be collected in condenser 14. As the level ofliquid system charge 30 increases in condenser 14, the liquid systemcharge will flow through and be collected in the condenser in a reverseorder to the normal direction of flow of the system charge. For example,liquid system charge 30 will first be collected in outlet manifold 34-1,fourth pass 16-4, and third return manifold 36-3. The collection ofliquid system charge 30 continues until the liquid level reaches bottomconduit 38-2. Once the fluid level reaches bottom conduit 38-2, theliquid system charge 30 is collected in tank 12, as well as theremaining portions of condenser 14.

Thus, in FIG. 4, tank 12 is positioned on first return manifold 36-1 sothat the flow of system charge 30 through first and second conduits38-1, 38-2 is in a vertical direction.

Thus, in the embodiment of FIG. 4, tank 12 is positioned on first returnmanifold 36-1 so that flow of system charge 30 through first and secondconduits 38-1, 38-2 is in a vertical direction.

It should be noted that tank 12 is described in use with condenser 14.However, it is contemplated by the present disclosure for tank 12 tofind equal use with evaporator 20.

It should also be noted that the terms “first”, “second”, “third”,“upper”, “lower”, and the like may be used herein to modify variouselements. These modifiers do not imply a spatial, sequential, orhierarchical order to the modified elements unless specifically stated.

While the present disclosure has been described with reference to one ormore exemplary embodiments, it will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted for elements thereof without departing from the scope of thepresent disclosure. In addition, many modifications may be made to adapta particular situation or material to the teachings of the disclosurewithout departing from the scope thereof. Therefore, it is intended thatthe present disclosure not be limited to the particular embodiment(s)disclosed as the best mode contemplated, but that the disclosure willinclude all embodiments falling within the scope of the appended claims.

1. A mini-channel heat-exchanger for a refrigeration circuit,comprising: an inlet manifold; a first return manifold; a first heatexchange pass in fluid communication between said inlet manifold andsaid first return manifold, said first heat exchange pass including aplurality of mini-channels; and a system charge tank in direct fluidcommunication with said first return manifold.
 2. The heat-exchanger asin claim 1, further comprising an outlet manifold and a second heatexchange pass, said second heat exchange pass being in fluidcommunication between said first return manifold and said outletmanifold.
 3. The heat-exchanger as in claim 1, further comprising: afirst conduit placing top portions of said first return manifold andsaid system charge tank in direct fluid communication with one another;and a second conduit placing bottom portions of said first returnmanifold and said system charge tank in direct fluid communication withone another.
 4. The heat-exchanger as in claim 3, wherein said systemcharge tank is positioned on said first return manifold so that saidfirst and second conduits are configured for flow in a horizontaldirection.
 5. The heat-exchanger as in claim 3, wherein said systemcharge tank is positioned on said first return manifold so that saidfirst and second conduits are configured for flow in a verticaldirection.
 6. The heat-exchanger as in claim 3, wherein said firstreturn manifold and said system charge tank are integrally formed withone another and said first and second conduits comprise holes.
 7. Theheat-exchanger as in claim 6, wherein said system charge tank has a tankfloor and said first return manifold has a manifold floor, said secondconduit being substantially co-planar with said tank and manifoldfloors.
 8. The heat-exchanger as in claim 3, wherein said first returnmanifold and said system charge tank are remote from one another andsaid first and second conduits comprise pipes.
 9. The heat-exchanger asin claim 1, wherein said system charge tank has a tank length and saidfirst return manifold has a manifold length, said tank length beingsubstantially equal to said manifold length.
 10. The heat-exchanger asin claim 1, wherein said system charge tank has a tank floor and saidfirst return manifold has a manifold floor, said tank floor beingco-planar with or slightly higher than said manifold floor.
 11. A methodof performing a system pumpdown in an air conditioning system having arefrigeration circuit, the method comprising the steps of: closing afirst valve; running a compressor until all of a system charge has beencompressed between said compressor and said first valve and liquidsystem charge fills a portion of a mini-channel heat-exchanger and asystem charge tank, said system charge tank being fluidly connected tosaid mini-channel heat-exchanger.
 12. The method of claim 11, furthercomprising closing a second valve after said compressor is turned off.13. The method of claim 12, further comprising opening said first andsecond valves so that said system charge can be recirculated throughoutthe refrigeration circuit.
 14. A refrigeration system, comprising: acondenser having an inlet manifold, a first return manifold, a firstheat exchange pass in fluid communication between said inlet manifoldand said first return manifold, said first heat exchange pass includinga plurality of mini-channels, and a system charge tank in direct fluidcommunication with said first return manifold; a compressor; and anevaporator.